Recent papers have demonstrated that S100A protein family played key roles in cancer metastasis and pre-metastatic niche formation.25 In addition, S100A4 might be vital for cancer stemness and metastasis.15,26–28 Consistently, our data showed that S100A4 expression in HCC cell lines and cell line derived exosomes were positively correlated with metastatic potential of these cell lines. The gene discussed is S100A1; the disease is cancer.